Canal Locks

A Narrow Boating Article.

In the UK just about every inland waterway will have some type of lock and this adds to the fun of travelling on a canal boat. Locks are devices for raising or lowering narrow boats between stretches of water. It may seem an impossible idea but it some places they can raise or lower the canal as much as 220 feet. The Tardebigge Locks, for example, raises the Worcester and Birmingham Canal to this height over a distance of two and a quarter miles.

Just think of a lock as a chamber that is closed off by gates. These gates are opened or closed to control the water level allowing it, and your canal boat, to be lowered or raised. Locks have two sets of gates a top and bottom one. They also have sluice gates, openings, at the top and bottom. By opening these, using a *windlass water is allowed in and out of the chamber to raise or lower the level.

*What is a windlass? - A windlass is a lock key used to turn the gear which winds up the paddles to allow water in or out of the lock. A windlass will be part of the equipment supplied on the canal boat

If you are going narrow boating for the first time take a look at our detailed guide to locks

What is a lock?

A lock is a section of canal that can be closed off.

What is a flight of locks?

A flight of locks look like a flight of stairs and consists of a number of locks, or steps, one after another. Sometimes there is a stretch of canal between one lock and the next, and sometimes the locks are so close together that the top gates of one and the bottom gates of the next are one and the same

What is a manned lock?

Some locks such as the Foxton Flight on the Grand Union Canal near to Market Harborough are manned by friendly lockkeepers. It is their job to guide you through these locks and they will instruct you on what colour paddle to open, depending on where they wants to send the water.

How do you work a lock?

Locks have two sets of gate a top and bottom one. They also have a chamber which you, your boat enters into. They have openings,or sluice gates, at the top and bottom and it is by opening these that water is allowed into and out of the chamber to raise or lower the water level. You and your crew will open and close the paddles using a *windlass.

Going up

1. Open the lock gate and take the boat into the lock. Remember to close the gate behind the boat

2. Open the sluice gate to allow the water to flow from the top pound into the lock

3. The boat will rise as the lock fills

4. Once the water level inside the lock is the same as the water level ahead in the canal, open the top gates and take the boat out

5. Remember to close both the sluice gate and the lock gate behind you to preserve water

Going down

1. Open the lock gate and take the boat into the lock. Remember to close the gate behind the boat

2. Open the sluice gate to allow the water to flow out of the lock

The boat will lower as the water level in the lock falls

Once the water level inside the lock is the same as the water level ahead in the canal, open the bottom gates and take the boat out.

Remember to close both the sluice gate and the lock gate behind you to preserve water

How long does it take?

Passing through a lock will generally take between 10 to 20 minutes so in some cases, such as the locks known as Heartbreak Hill, you should allow a whole day. These locks located on the Trent and Mersey Canal consist of 26 locks spread over 7 miles.

Basic principles

Water always flows downhill and lock gates are closed against the pressure of this water. The lock gates will not open until the water pressure or level is equal on both sides.

Keep safe in the lock area by

Paying attention to what is going on around you

Taking care when walking on slippery surfaces

Keeping children away from the edge of the lock chamber

Keeping pets inside the canal boat

Not dangling hands or feet over the edge of the canal boat

Not standing or sitting on the roof of the canal boat

Not leaving your windlass on the lock mechanism unattended

When using your windlass keep your fingers, hair and clothing out of the gears

Do not let go of the windlass whilst operating the lock gears – 'spinning' may cause injury

Terminology

Chamber - The main feature of a lock, it is a watertight enclosure which can be sealed off from the pounds at either end by gates.

Cill - A ledge inside the lock on which the gates sit. Gates are watertight doors which seal off the chamber from the pounds. Each end of the chamber is equipped with a gate made of oak, elm or steel.

Guillotine lock - A lock where the gate is wound upwards like the blade of a guillotine.

Lock flights - A series of locks in close enough proximity with a short pound in between.

Lock Keepers - Some locks are operated or supervised by professional Lock Keepers, in particularly where locks are large or have complicated features.